Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> writes: > On Wed, 27 Aug 2025 at 17:37, Puranjay Mohan <puranjay@xxxxxxxxxx> wrote: >> >> Changes in v3->v4: >> v3: https://lore.kernel.org/all/20250827150113.15763-1-puranjay@xxxxxxxxxx/ >> - Fixed a build issue when CONFIG_BPF_JIT=y and # CONFIG_BPF_SYSCALL is not set >> >> Changes in v2->v3: >> v2: https://lore.kernel.org/all/20250811111828.13836-1-puranjay@xxxxxxxxxx/ >> - Improved the selftest to check the exact fault address >> - Dropped BPF_NO_KFUNC_PROTOTYPES and bpf_arena_alloc/free_pages() usage >> - Rebased on bpf-next/master >> >> Changes in v1->v2: >> v1: https://lore.kernel.org/all/20250806085847.18633-1-puranjay@xxxxxxxxxx/ >> - Changed variable and mask names for consistency (Yonghong) >> - Added Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx> on two patches >> >> This set adds the support of reporting page faults inside arena to BPF >> stderr stream. The reported address is the one that a user would expect >> to see if they pass it to bpf_printk(); >> >> Here is an example output from a stream and bpf_printk() >> >> ERROR: Arena WRITE access at unmapped address 0xdeaddead0000 >> CPU: 9 UID: 0 PID: 502 Comm: test_progs >> Call trace: >> bpf_stream_stage_dump_stack+0xc0/0x150 >> bpf_prog_report_arena_violation+0x98/0xf0 >> ex_handler_bpf+0x5c/0x78 >> fixup_exception+0xf8/0x160 >> __do_kernel_fault+0x40/0x188 >> do_bad_area+0x70/0x88 >> do_translation_fault+0x54/0x98 >> do_mem_abort+0x4c/0xa8 >> el1_abort+0x44/0x70 >> el1h_64_sync_handler+0x50/0x108 >> el1h_64_sync+0x6c/0x70 >> bpf_prog_a64a9778d31b8e88_stream_arena_write_fault+0x84/0xc8 >> *(page) = 1; @ stream.c:100 >> bpf_prog_test_run_syscall+0x100/0x328 >> __sys_bpf+0x508/0xb98 >> __arm64_sys_bpf+0x2c/0x48 >> invoke_syscall+0x50/0x120 >> el0_svc_common.constprop.0+0x48/0xf8 >> do_el0_svc+0x28/0x40 >> el0_svc+0x48/0xf8 >> el0t_64_sync_handler+0xa0/0xe8 >> el0t_64_sync+0x198/0x1a0 >> >> Same address is seen by using bpf_printk(): >> >> 1389.078831: bpf_trace_printk: Read Address: 0xdeaddead0000 >> >> To make this possible, some extra metadata has to be passed to the bpf >> exception handler, so the bpf exception handling mechanism for both >> x86-64 and arm64 have been improved in this set. >> >> The streams selftest has been updated to also test this new feature. > > We also need arm64 experts to take a look before we land, since you'll > respin anyway now. > Xu, could you please provide acks on the patches? > > Thanks a lot. Thanks for your review. I will wait for Xu's feedback before respining. Thanks, Puranjay
